I have this irrational fear of swimming close to boat propellers. Ever since I watched the movie finding Nemo when I was young, seeing his dad nearly being torn up by the propellor. It gave me shivers.
Yes there is cavitation and it is not what is coming out of the rear which is exhaust but around the blade, this is inherent to the quality of this blade
Theres a small cavitation on the prop flukes at full speed but its normal for the type of prop and the angle of the flukes and the stream you see shooting out from the middle of the prop is the exhaust , not heavy cavitation
hello, it look great. i need a little help about the selection of motor with regards the weight of the ROV , example, if you move a 20 kg ROV at speed of 4 knot in salt water , then how you select the motor, how much thrust you required to move with constant speed? if you have any material or formula, please help me into this.
The exhaust gasses come out of the back of the engine hood (above water) while idling, only when an outboard throttles up in gear they gasses come out of the propeller. The bubbles at the end of the blades is a light form of cavitation. Water boiling because of the low pressure. Think its an aluminium prop as it occurs quite soon. A stainless prop has better performance.
Per quello purtroppo il bastone della Gopro non può essere d'aiuto, sto pensando di immergerla in un fondale di circa 1,5 metri, e navigare sopra la camera che poi dovrei recuperare, purtroppo lavorando in estate non ho il tempo di fare tutto quello che vorrei.
And this is why a sportfish vessel will out fish every outboard. Harmonic and no exhaust trail make it extremely clear for your baits behind boat look deadly
that was ventilation as the boats not moving but the water is it sucked air from above the anti-ventilation plate and then held it. you should come off the throttle then back on it again.
Outboard engines have their exhaust through the propeller. Cavitation happens on the front side of the leading edge and on the tip of the propeller due to suction and vortex.
This is meaningless. The hydrodynamics of an engine/propeller pair running while being held stationary, is NOTHING like the flow while it is moving. The flow of water past a prop in motion does not behave this way. What you are showing is a 100% slip situation. In actual use, a prop only slips a small percentage. What happens behind it in those two conditions is way different.
The bubbles comminf from the center of the prop are an exhaust trail. The bubbles forming at the edges of the prop are cavitation. When water pressure decreases, so does the boiling point of water. The back side of the prop creates a low pressure when quickly displacing water. This low pressure causes the water to "boil" and that is what causes the bubbles.
@@leemilica Little ones don't bother me. It's the huge propellers underwater that do. And it's not because I'm a crybaby. I watch and play horror games and movies daily XD
I have Submechanophobia and this doesn’t trigger me an awful lot but I wouldn’t swim next to even a prop this small Edit: Submechanophobia is we’re you have a fear of something large submerged under water, for me propellers, large underwater structure and anchors are the worst.
This is NOT CAVITATION!!! People should know what they are talking about before spewing ignorant comments on YT !! A outboard engine exhaust comes out the center of the prop, that’s exhaust not cavitation!!
If you ever fired up an outboard engine outside the water (to wash the cooling system with fresh water), you would notice that, in fact, the exhaust is at the center of the propeller. That is not all cavitation. Cavitation bubbles would appear mostly at the blades, not at the center. The blades are engineered to keep caviatation to a bare minimum. Since the engine is being accelerated, the amount of air passing the combustion is so large it makes that bubble tail.
Youssif Galal either you don’t have an outboard or you have some weird model with an odd exhaust system. Nearly all outboards have the main exhaust coming from the center of the prop. When it’s in neutral there is minimal exhaust coming from that vent. There was some cavitation on this blade but the main source of the turbulence is from exhaust.
That is ventilation, not cavitation. Cavitation is when the propeller pulls air to it from the surface. That is why an anti-cavitation plate is positioned between the waterline and the propeller. Ventilation comes from drilling holes in the exhaust ports of the prop to let exhaust out at the fins of the propeller, thus causing less drag which allows the engine to spin a bit easier. It helps the boat get on a plane faster.
Wrong. When water pressure decreases, so does the boiling point of water. The back side of the prop creates a low pressure when quickly displacing water. This low pressure causes the water to "boil" and THAT is where the air comes from. This is cavitation.
I have this irrational fear of swimming close to boat propellers. Ever since I watched the movie finding Nemo when I was young, seeing his dad nearly being torn up by the propellor. It gave me shivers.
Buy a stick for the gopro and fear will disappear! Voila!
Submechaniphobia. Look it up man
Okay, now I know what my newest nightmare's gonna be -- getting stuck too close to a boat propeller going at full blast.
Thanks for that. 👍
ua-cam.com/video/UYrSXmkO6Nk/v-deo.html
Thank you very much for the opportunity to see the cavitation underwater. Brilliant video.
Nicely done
very interesting
The last test look really safe!
They have a fetish with getting their fingers chopped off
Or thet use a pole for the GoPro.
calm your tits. just because a camera is near something doesnt mean a person is near it
@@dirtrider88 haha calm your tits ohh that's hilarious
@@lucavanzi can you get a joke?
I'm watching this because it looks like a fan.
Im watching this because it looks fan.
Cool! It looks strong.
Thank you sir, knowledge is power 👍
It was one of my first videos with gopro. Next time I'gonna shoot in 720/240 fps and then slow down even more.
Yes there is cavitation and it is not what is coming out of the rear which is exhaust but around the blade, this is inherent to the quality of this blade
It looks like an aluminium prop, so it is what it is.
Theres a small cavitation on the prop flukes at full speed but its normal for the type of prop and the angle of the flukes and the stream you see shooting out from the middle of the prop is the exhaust , not heavy cavitation
how can we minimize cavitation by changing its design?
By making greater propeller wings, maybe use different angles for different speeds and cooling the prop
Is that a yamaha 60 outboard as i have one and it looks identical
Why has the inlet been blocked off?
Surprisingly quiet. I thought it got louder when your further away due to that buzzing sound
That last part took the breath outta me.. I thought he was gonna get pulled in from the side!
"Conn, sonar sierra 1 is cavitating"
A fellow cold waters player? I see you're a man of culture as well
hello,
it look great. i need a little help about the selection of motor with regards the weight of the ROV , example, if you move a 20 kg ROV at speed of
4 knot in salt water , then how you select the motor, how much thrust you required to move with constant speed? if you have any material or formula, please help me into this.
Did u get ur answer?? If so, plz tell.. I too have the same doubt
I love that little whirlpool at the top
Funny how you can't see exhaust coming out when the engine is idling.
I expected to see bubbles even then.
Probably has exhaust ports on the leg like my evinrude
Wait the exhaust comes out the propellers
@@allgaming4045 Well, the hub.
@@allgaming4045 It's called through hub exhaust. Most common thing on outboards.
The exhaust gasses come out of the back of the engine hood (above water) while idling, only when an outboard throttles up in gear they gasses come out of the propeller. The bubbles at the end of the blades is a light form of cavitation. Water boiling because of the low pressure. Think its an aluminium prop as it occurs quite soon. A stainless prop has better performance.
WOW COOL!!!!!
What’s the air that are coming out?
Cavitation happens with all props, its high engine torque or rpm that causes it. Slow rpm after holeshot cavitation will stop.
thank you for sharing!
Video molto interessante🔝, sarebbe bello poter vedere questo effetto con barca in movimento...
Per quello purtroppo il bastone della Gopro non può essere d'aiuto, sto pensando di immergerla in un fondale di circa 1,5 metri, e navigare sopra la camera che poi dovrei recuperare, purtroppo lavorando in estate non ho il tempo di fare tutto quello che vorrei.
Is there ment y to be a water jet in the middle of propeller
That is cool
I don't even own a boat nor have I ever even been on a boat, why am I watching this
It's called curiosity. Till now you have good curiosity though. I hope you never have bad.
And this is why a sportfish vessel will out fish every outboard.
Harmonic and no exhaust trail make it extremely clear for your baits behind boat look deadly
that was a great video of a propeller I wish I could see one in real life !
I can tell you I own an out drive but would never go down there to see it
I hope you never see one by falling out of a boat and being sucked onto it
im tired.
thanks.
maybe putting a cage around the fan, block fish from getting slashed by propeller
But also fuck up the water dynamics of it
Have you grown up?
When the fuck has anyone chopped up a stupid fish with it
@@James-xc9zy LOL. He could've at least said manatee lol. Fish swim out the way long before boats get to them
Then the fish will just be fish food...
@@James-xc9zy alot of people have asshole
@@rev9fan1 fish are friends not food
that was ventilation as the boats not moving but the water is it sucked air from above the anti-ventilation plate and then held it. you should come off the throttle then back on it again.
It is the water behind the propeller boiling due to low pressure, not air. This is cavitation.
Outboard engines have their exhaust through the propeller. Cavitation happens on the front side of the leading edge and on the tip of the propeller due to suction and vortex.
The best
it's cavitating , it can damage the shaft due to vibrations
Why the engine is so small??
What type of engine is that?
Mohdaliffhassan Hassan thats a yamaha , probably a F50 or F60
Yamaha
is this terrifying to anyone else
No
@@Moog604 😔
Yamaha
This is meaningless. The hydrodynamics of an engine/propeller pair running while being held stationary, is NOTHING like the flow while it is moving. The flow of water past a prop in motion does not behave this way. What you are showing is a 100% slip situation. In actual use, a prop only slips a small percentage. What happens behind it in those two conditions is way different.
I was about to say the same thing but you beat me to it 😂
I dunno about marine propeller engines but
In aircraft engines there are two types of thrusts commonly referred, installed and uninstalled thrust.
Bro shut up enjoy the video
Who cares about hydrodynamics here?
I think it was cool to watch.
Still looks cool
I know it's a tiny propeller but this still scares me
I wonder Where did the air bubbles come from underwater ?
The water is actually boiling. High pressure causes this.
Or maybe it’s lower pressure. Forget which one.
Mooring is OK!? Hello from Saint -Petersburg Russia! Chmoki!
can someone explain to me the bubbles
The bubbles comminf from the center of the prop are an exhaust trail. The bubbles forming at the edges of the prop are cavitation. When water pressure decreases, so does the boiling point of water. The back side of the prop creates a low pressure when quickly displacing water. This low pressure causes the water to "boil" and that is what causes the bubbles.
I needed to know what one looked like because I was drawing one !
And this test proves ? Throw a hydrofoil on it and compare . (Something) lol
It proves nothing. But you can determine how bad your prop cavitates.
what happens when a person comes in?
He dies
They die
Which motor used for this?
Yamaha 60 outboard
This is how to create oxygen under water.So that you breathing like a fish.
палец не пробовал засунуть?
That's a lot of Cavitation
Not neccesarily .
Subnautica?
why do you think this is not cavitation ?
A little bit of both of you know what I mean
Hardcore Gaming exhaust
lot of cavitation
Thats mostly because its standing still
Why not upload in 1080P 60fps?
Submechanophobia
[ Agressia ] if you are a crybaby. How can this little propeller scare you?
@@leemilica
Little ones don't bother me. It's the huge propellers underwater that do. And it's not because I'm a crybaby. I watch and play horror games and movies daily XD
@@deadanimasher678 underwear?
@@deadanimasher678 just like me
@@deadanimasher678 Same here :(
@ 5:15 ...
0:28 udaranya muncul dari mana ya?
That's the exhaust
Biker
I have Submechanophobia and this doesn’t trigger me an awful lot but I wouldn’t swim next to even a prop this small
Edit: Submechanophobia is we’re you have a fear of something large submerged under water, for me propellers, large underwater structure and anchors are the worst.
I googled this and clicked images... Yeah fuck that.
This is NOT CAVITATION!!! People should know what they are talking about before spewing ignorant comments on YT !! A outboard engine exhaust comes out the center of the prop, that’s exhaust not cavitation!!
dude your so wrong. Exhaust comes from above, when engine is idle there are no bubbles coming out. Its cavitation
Still have one blade cavitating as well
you can literally see cavitation coming from the blades,
What the f*** is wrong with you?
If you ever fired up an outboard engine outside the water (to wash the cooling system with fresh water), you would notice that, in fact, the exhaust is at the center of the propeller. That is not all cavitation. Cavitation bubbles would appear mostly at the blades, not at the center. The blades are engineered to keep caviatation to a bare minimum. Since the engine is being accelerated, the amount of air passing the combustion is so large it makes that bubble tail.
Youssif Galal either you don’t have an outboard or you have some weird model with an odd exhaust system. Nearly all outboards have the main exhaust coming from the center of the prop. When it’s in neutral there is minimal exhaust coming from that vent. There was some cavitation on this blade but the main source of the turbulence is from exhaust.
That is ventilation, not cavitation. Cavitation is when the propeller pulls air to it from the surface. That is why an anti-cavitation plate is positioned between the waterline and the propeller. Ventilation comes from drilling holes in the exhaust ports of the prop to let exhaust out at the fins of the propeller, thus causing less drag which allows the engine to spin a bit easier. It helps the boat get on a plane faster.
Wrong. When water pressure decreases, so does the boiling point of water. The back side of the prop creates a low pressure when quickly displacing water. This low pressure causes the water to "boil" and THAT is where the air comes from. This is cavitation.
cavitation from hell
Toy ship
no catalytic converter no nothing. Just dump the exaust into the ocean. disgusting and disgraceful!